Fluid-filled mounts for damping vibrations imparted on one axis have been known for quite some time. Such mounts generally include a fluid-filled pumping chamber in fluid communication with a receiving chamber via a conduit. The conduit may be sized and shaped to provide a fluid slug which resonates at a particular frequency to enable the stiffness of the mount to be controlled within a preselected frequency range. Such mounts have found particular utility in mounting engines in automobiles. An example of such a mount is disclosed in U.S. Pat. No. 4,712,777, owned by the assignee of the present application.
For applications requiring damping along two perpendicular axes, a fluid-filled isolator such as disclosed in U.S. Pat. No. 4,424,960 has been proposed. Such an isolator incorporates a pair of lateral fluid chambers in addition to a pair of vertical fluid chambers to damp vibrations both in a vertical direction and in a single horizontal direction. While this patented isolator may function satisfactorily for its intended purpose, there is a need for an isolator which can also damp vibrations imparted in three orthogonal directions such as for use in mounting avionics in aircraft. While various structures have been proposed for such purposes, such as described in U.S. Pat. Nos. 2,540,130; 2,295,829; 2,668,033; 3,721,417; 3,874,646, and 4,667,942 none of these patented mounts meets all of the requirements of a desirable multi-axis avionics mount.